I reckon you should do your own thing. I use Ernie Ball Regular Slinkies (10-52) on my Mustang. They are great, and seem to last for aaaages.
It's all really down to you as a player. If Kurt used 13s, maybe that was because he liked it that way. You might find that you can't really deal with them as easily as, say 9s or 10s. It also depends on what scale length your guitar is... In my opinion, short short scales (like 22.5") should have 12s or 13s. For 24" and standard Gibson scale, I'd suggest 10s, and on 25.5, I'd go 9s. But that's just me. Play about and see what best suits you, don't just do something cause your idol does (or did) it.
